The two conventional types of traveling cranes, which differ substantially from one another depending on whether the arm is pivoted on the crane bed or on a proper tower-shaped vertical upright, having the following operational limitations:
With the first, it is possible to operate at the maximum straddle only on spaces which are free near the crane. Indeed, the presence of bulky obstacles would hinder the free opertion of the jib which, when at a minimum slant, is comparatively low.
In the second type, the jib articulation placed at a certain height permits the crane to easily operate with front obstacles in the working area, but it has the disadvantage of leading to a remarkable increase in the total height of the crane when handling loads placed near it. Indeed, in these work conditions, the total height tends to reach a value equal to the height of the jib plus the height of its articulation joint.